With the development of smart devices, image sensors including a photodiode are required to have high resolution. However, in the case of a photodiode using silicon which is currently mainly used, it is difficult to decrease the thickness thereof, and there is a limit in increasing the absorbance thereof.
Accordingly, an organic photodiode having high absorbance and various absorption wavelengths has drawn attention as a material replacing a silicon diode, but the existing organic photodiode has a problem in that the efficiency thereof deteriorates in a visible light region as compared to that of the silicon diode. To solve the problem, there is a need for studying organic materials for the organic photodiode.